#ident "$URL: svn://elmer/devel/SVN/SDDAS/trunk/libant/LinkInsert.c $ %D% SwRI"
/* LinkInsert.c -- insert node into list various ways */
 
#include "LinkList.h"

/* LinkInsert  -- insert data into sorted list */
LinkList LinkInsert(
LinkList  list,
void  *data,
LinkFun  compare)
{
  LinkList NewNode;

  NewNode = LinkCreate(data);
  if (!list)
    list = NewNode;
  else if ((*compare)(data,list->data) <= 0)
    {
      NewNode->next = list;
      list = NewNode;
    }
  else
    {
      LinkList p;
      for (p=list; p->next; p=p->next)
	if ((*compare)(data,p->next->data) <= 0) 
	  break;
      NewNode->next = p->next;
      p->next = NewNode;
    }
  return list; 
}

/* LinkInsertAfter -- insert data after node with reference data */
LinkList LinkInsertAfter(LinkList  oldlist,void  *ref_data,void  *data)
{
  LinkList list;		/* used to traverse oldlist                  */

  for (list=oldlist; list; list=list->next)
    if (list->data == ref_data)
      {
	list->next = LinkPush(list->next,data);
	return oldlist;
      }
  return LinkAppend(oldlist,data);
}

/* LinkInsertAt -- insert data at position n (0=first,-1 or too big= end) */
LinkList LinkInsertAt(LinkList  oldlist,int  n,void  *data)
{
  LinkList list;		/* used to traverse oldlist                  */
  LinkList prev;		/* previous node in list                     */

  if (n < 0)
    return LinkAppend(oldlist,data);
  if (n == 0)
    return LinkPush(oldlist,data);

  for (prev=oldlist,list=oldlist->next; list; prev=list,list=list->next)
    if (--n == 0)
      {
	prev->next = LinkPush(list,data);
	return oldlist;
      }
  return LinkAppend(oldlist,data);
}

/* LinkInsertBefore -- insert data before node with reference data */
LinkList LinkInsertBefore(LinkList  oldlist,void  *ref_data,void  *data)
{
  LinkList list;		/* used to traverse oldlist                  */
  LinkList prev;		/* previous node in list                     */

  if (oldlist->data == ref_data)
    return LinkPush(oldlist,data);

  for (prev=oldlist,list=oldlist->next; list; prev=list,list=list->next)
    if (list->data == ref_data)
      {
	prev->next = LinkPush(list,data);
	return oldlist;
      }
  return LinkAppend(oldlist,data);
}